JBMO-SL 2011 C6

Let $n>3$ be a positive integer. An equilateral triangle $\triangle A B C$ is divided into $n^{2}$ smaller congruent equilateral triangles (with sides parallel to its sides).

Let $m$ be the number of rhombuses that contain two small equilateral triangles and $d$ the number of rhombuses that contain eight small equilateral triangles. Find the difference $m-d$ in terms of $n$.